Which of the following elements is a liquid at room conditions?
A. sulphur
B. mercury
C. potassium
D. argon
Which of the following statements about metals and non-metals is correct?
A. They are about equal numbers of both.
B. They can be easily distinguished by their appearance.
C. All metals are high-melting solids; all non-metals are gases or low-meiting solids.
D. There are more than 100 metals and non-metals altogether.
lron pyrite(FeS2 ) looks like gold and its common name is "fool's gold". Which of the following methods can be used to distinguish iron pyrite from gold?
(1) comparing their densities
(2) comparing their electrical conductivity
(3) comparing the effect of heat on them
A. (1) and (2) only
B. (1) and (3) only
C. (2) and (3) only
D. (1) ,(2)and (3)
Would you classify the following element/compounds as a metal or non-metal? Why?
(a) water
(b) graphite
(c) mercury
Decide which id the odd one in each of the following groups of elements. Give reason(s) for your choice in each case.
(a) iron, copper, mercury, silver
(b) magnesium, sulphur, lead, tin
(c) iodine, oxygen, nitrogen, argon
(d) phosphorus, bromine, helium, carbon(in the form of graphite)
The statements below are about metals, non-metals and semi-metals. State whether each of them is ture or false and give your reasons.
(a) If the element is a gas at room conditions, it must be a non-metal.
(b) If the element is a liquid at room conditions, it must be a non-metal.
(c) If the element can conduct electricity, it must be a metal or a semi-metal.
(d) If the element is a soft solid at room conditions, it must be a non-metal.
(e) If the element is a red solid at room conditions, it must not be a metal.
Which of the following metals is/ are extracted bt electrolysis?
(1) lead
(2) calcium
(3) potassium
A.(1) only
B. (2) only
C. (1) and (3) only
D. (2) and (3) only
chem about metals bt
2012-02-28 3:27 am
回答 (2)
2012-02-28 5:25 am
✔ 最佳答案
1.B2.D
3.A
4(a)Only an element can be classified as a metal or non-metal. Water is not
an element.
4(b)Non-metal.It is dull in appearance and low density although it is a electrical conductor.
4(c)Metal,it has high density and it is a electrical conductor
5(a)Mercury. All are metals. Mercury is a liquid, while the others are solids at room conditions. 5(b) Sulphur . Sulphur is a non-metal, while the others are metals.5(c)Iodine. All are non-metals. Iodine is a solid, while the others are gases at room conditions.
5(d)Graphite. All are non-metals. Graphite conducts electricity, while the others are non-conductors of electricity.
6(a)True
6(b)False.Mercury is a liquid metal at room condition
6(c)False.Carbon in the form of graphite can conduct electricity.
6(d)False.Group I elements(Alkali metals) are soft metals which can be cut easily.
6(e)True.
7.D
2012-02-28 02:28:59 補充：
For Q3,sorry for making a mistake.
Note that iron pyrite is an ionic compound,thus it has a giant ionic structure.
While gold has a giant metallic structure.
Gold has a good thermal conductivity due to the presence of delocalized electrons.
2012-02-28 02:29:04 補充：
For Q6e,the colour of copper should be reddish brown instead of red.
2012-02-28 6:35 am
1. B
check that liquids have room temp. in between melting point & boiling point.
2. D
not A: check the periodic table.
not B: metallic elements on right hand side have some properties of non-metals, making them difficult to be distinguished.
not C: mercury VS garbon (graphite, diamond)
3. D
opt. (3): look at the melting point / decomposition temp. / thermal conductivity.
4a. no classification for compounds.
4bc.
how does one classify metals / non-metals?
not by electrical conductivity (graphite)
not by melting point (mercury) ....
should see whether the element is malleable / ductile / has typical chemical properties of metals.
5. many possible answers. give you hints, think yourself:
a. physical state? color?
b. metals? color?
c. physical state? color? number of atoms per molecule?
d. electrical conductivity? color? simple/giant covalent structure?
6a. true
6b. mercury..
6c. graphite..
6d. sodium..
6e. copper..
7. D
2012-02-28 05:06:19 補充：
copper: that depends on how you judge what is "red".
of course it's not that red compared to red phosphorus, but when compared to other silvery metals, especially when oxide layer of copper has been removed..
check that liquids have room temp. in between melting point & boiling point.
2. D
not A: check the periodic table.
not B: metallic elements on right hand side have some properties of non-metals, making them difficult to be distinguished.
not C: mercury VS garbon (graphite, diamond)
3. D
opt. (3): look at the melting point / decomposition temp. / thermal conductivity.
4a. no classification for compounds.
4bc.
how does one classify metals / non-metals?
not by electrical conductivity (graphite)
not by melting point (mercury) ....
should see whether the element is malleable / ductile / has typical chemical properties of metals.
5. many possible answers. give you hints, think yourself:
a. physical state? color?
b. metals? color?
c. physical state? color? number of atoms per molecule?
d. electrical conductivity? color? simple/giant covalent structure?
6a. true
6b. mercury..
6c. graphite..
6d. sodium..
6e. copper..
7. D
2012-02-28 05:06:19 補充：
copper: that depends on how you judge what is "red".
of course it's not that red compared to red phosphorus, but when compared to other silvery metals, especially when oxide layer of copper has been removed..
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